Current thinking is that the hunger and satiety centers of the hypothalamus play an important role in regulating food intake. Little is known, however, regarding details that surround the basic mechanisms in control of food intake. We have evidence to show that the amount of food consumed during suckling plays an important role in determining the habitual food intake of rats in later life. One objective of our work is to investigate the effect of early nutritional manipulation on food intake, body size, and the cellular character of certain organs. A second objective is to elucidate the role of early nutritional manipulation on insulin insensitivity in adipose tissue. A third objective is to elucidate the role of hormone(s) in the proliferation of adipocytes.